PROJECT SUMMARY/ABSTRACT Human communication and other listening behaviors often take place in acoustically complex, or noisy environments like schools, restaurants, and workplaces. Much of daily life requires us to select behaviorally- relevant auditory dimensions, and potentially suppress irrelevant dimensions, so that the information conveyed can be remembered and responded to appropriately. Unfortunately, this vital everyday ability is affected by many neurological conditions resulting in marked decreases in quality of life. Despite the importance of auditory selective attention, its cognitive and neural mechanisms are poorly understood. For example, although auditory selective attention is widely presumed to involve both a selective enhancement of behaviorally relevant auditory dimensions and suppression of dimensions outside this attentional focus, evidence for suppression is scant. The long-term goal of the proposed research is to arrive at a mechanistic understanding of auditory selective attention. The present project pursues the central hypothesis that human auditory selective attention is a result of processes related to both enhancement (of task-relevant sounds) and suppression (of task-irrelevant sounds). Preliminary studies establish a nonspeech experimental paradigm for engaging - and improving ?auditory selective attention directed to specific frequency bands, and for non-invasively mapping it across auditory cortex using multimodal MRI. A parallel preliminary study establishes that attention training drives improvements in behavioral and electrophysiological measures of auditory selective attention. Aim 1 will determine the fine- grained ?listening window? through which auditory selective attention prioritizes and selects behaviorally relevant auditory dimensions, and potentially suppresses irrelevant dimensions. These studies also will determine the extent to which tasks and expectations created from input regularities shape the listening window. Aim 2 will assess changes in the spectrotemporal shape of the auditory attentional filter as listeners learn to more efficiently deploy auditory selective attention to specific dimensions. Aim 3 will identify the neurobiological underpinnings of auditory selective attention and their changes across improvements in selective attention. In all, the proposed research will weave together classic psychophysical approaches, behavioral training as a means to introduce targeted demands on selective attention, and newly-developed human neuroimaging tools to examine human auditory selective attention along the primary axis of auditory representation ? frequency. This will build a bridge from perceptuo-cognitive assays of human auditory selective attention to mechanistic electrophysiological and cellular/molecular studies thus far only undertaken with invasive nonhuman animal work, thereby compounding understanding and building a natural path toward future evidence-based approaches to the remediation of auditory attention impairments.